In high-speed and high-density signal transmission among electronic devices and among wiring boards, there are coming limitations in increase of transmission speed and density due to mutual interference and attenuation of signals as barriers in the conventional transmission by an electric wire. For overcoming the barriers, a technique of connecting among electronic devices and among wiring boards with light, i.e., a so-called optical interconnection, is being investigated.
A flexible film optical waveguide is demanded for transmitting an optical signal within a short distance inside a device or between devices. In the case where an optical waveguide is disposed inside a portable small-sized device, in particular, there are many cases where an optical waveguide is disposed to follow the surfaces of the parts for saving the space, and thus a polymer film optical waveguide that can be flexed with a small curvature radius is demanded.
An optical waveguide using a material having a low elastic modulus is developed for enhancing the bendability and the followability to the interface upon shape restoration of the optical waveguide. For example, Patent Documents 1 and 2 propose an optical waveguide with high flexural resistance and twist resistance having a flexural elastic modulus of the optical waveguide of 1,000 MPa or less and a thickness thereof of 150 μm or less. However, the optical waveguide is produced with a stamper, and there are defects of low degree of freedom in design and difficulty in design change.    [Patent Document 1] Japanese Patent No. 3,870,976    [Patent Document 2] Japanese Patent No. 3,906,870